Long term evolution interference management in unlicensed bands for wi-fi operation

ABSTRACT

Systems and methods for improved interference management by Wi-Fi devices are disclosed. The interference management may be achieved by monitoring, by the Wi-Fi device, signaling energy on a communication channel in a frequency band associated with the Wi-Fi device, comparing the monitored signal energy with a known waveform signature corresponding to Long Term Evolution (LTE) operation, and identifying a presence of an LTE interferer on the communication channel in the frequency band associated with the Wi-Fi device based on the comparison.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application for Patent is a Continuation of U.S. applicationSer. No. 14/275,505, entitled “LONG TERM EVOLUTION INTERFERENCEMANAGEMENT IN UNLICENSED BANDS FOR WI-FI OPERATION,” filed May 12, 2014,which in turn claims priority to U.S. Provisional Application No.61/891,227, entitled “METHODS TO DETECT LTE-U INTERFERENCE IN UNLICENSEDBANDS FOR EFFICIENT 802.11 WLAN OPERATION,” filed Oct. 15, 2013,assigned to the assignee hereof, and expressly incorporated herein byreference in its entirety.

INTRODUCTION

Aspects of this disclosure relate generally to telecommunications, andmore particularly to interference management in mixed radio accesstechnology environments and the like.

Wireless communication systems are widely deployed to provide varioustypes of communication content, such as voice, data, and so on. Typicalwireless communication systems are multiple-access systems capable ofsupporting communication with multiple users by sharing available systemresources (e.g., bandwidth, transmit power, etc.). Examples of suchmultiple-access systems include Code Division Multiple Access (CDMA)systems, Time Division Multiple Access (TDMA) systems, FrequencyDivision Multiple Access (FDMA) systems, Orthogonal Frequency DivisionMultiple Access (OFDMA) systems, and others. These systems are oftendeployed in conformity with specifications such as Third GenerationPartnership Project (3GPP), 3GPP Long Term Evolution (LTE), Ultra MobileBroadband (UMB), Evolution Data Optimized (EV-DO), Institute ofElectrical and Electronics Engineers (IEEE), etc.

In cellular networks, macro scale base stations (or macro (e)NodeBs)provide connectivity and coverage to a large number of users over acertain geographical area. A macro network deployment is carefullyplanned, designed, and implemented to offer good coverage over thegeographical region. Even such careful planning, however, cannot fullyaccommodate channel characteristics such as fading, multipath,shadowing, etc., especially in indoor environments. Indoor userstherefore often face coverage issues (e.g., call outages and qualitydegradation) resulting in poor user experience.

To extend cellular coverage indoors, such as for residential homes andoffice buildings, additional small coverage, typically low-power basestations have recently begun to be deployed to supplement conventionalmacro networks, providing more robust wireless coverage for mobiledevices. These small cell base stations are commonly referred to asfemto base stations, femto nodes, femto cell base stations, pico nodes,micro nodes, home NodeBs or home eNBs (collectively, H(e)NBs), etc., anddeployed for incremental capacity growth, richer user experience,in-building or other specific geographic coverage, and so on.

Recently, small cell LTE operations, for example, have been extendedinto unlicensed frequency bands such as the Unlicensed NationalInformation (UNII) band used by Wireless Local Area Network (WLAN)technologies. This extension of small cell LTE operation is designed toincrease spectral efficiency and hence capacity of the LTE system.However, it may also encroach on the operations of other radio accesstechnologies that typically utilize the same unlicensed band, mostnotably IEEE 802.11x WLAN technologies generally referred to as “Wi-Fi.”

There therefore remains a need for improved interference management byWi-Fi devices operating in the increasingly crowded unlicensed frequencybands without requiring each device to be provisioned with additionaland expensive LTE hardware.

SUMMARY

Systems and methods for providing for improved interference managementby Wi-Fi devices are disclosed.

A method for interference management by a Wi-Fi device is disclosed. Themethod may comprise, for example, monitoring, by the Wi-Fi device,signaling energy on a communication channel in a frequency bandassociated with the Wi-Fi device, comparing the monitored signal energywith a known waveform signature corresponding to Long Term Evolution(LTE) operation, and identifying a presence of an LTE interferer on thecommunication channel in the frequency band associated with the Wi-Fidevice based on the comparison.

An apparatus for interference management by a Wi-Fi device is alsodisclosed. The apparatus may comprise, for example, a signal energymonitor, a waveform comparator, and an interference identifier. Thesignal energy monitor may be configured to control monitoring, by theWi-Fi device, signaling energy on a communication channel in a frequencyband associated with the Wi-Fi device. The waveform comparator may beconfigured to compare the monitored signal energy with a known waveformsignature corresponding to LTE operation. The interference identifiermay be configured to identify a presence of an LTE interferer on thecommunication channel in the frequency band associated with the Wi-Fidevice based on the comparison.

Another apparatus for interference management by a Wi-Fi device is alsodisclosed. The apparatus may comprise, for example, a processor andmemory coupled to the processor for storing data. The processor may beconfigured to monitor, by the Wi-Fi device, signaling energy on acommunication channel in a frequency band associated with the Wi-Fidevice, compare the monitored signal energy with a known waveformsignature corresponding to LTE operation, and identify a presence of anLTE interferer on the communication channel in the frequency bandassociated with the Wi-Fi device based on the comparison.

Another apparatus for interference management by a Wi-Fi device is alsodisclosed. The apparatus may comprise, for example, means formonitoring, by the Wi-Fi device, signaling energy on a communicationchannel in a frequency band associated with the Wi-Fi device, means forcomparing the monitored signal energy with a known waveform signaturecorresponding to LTE operation, and means for identifying a presence ofan LTE interferer on the communication channel in the frequency bandassociated with the Wi-Fi device based on the comparison.

A computer-readable medium comprising instructions, which, when executedby a processor, cause the processor to perform operations forinterference management by a Wi-Fi device is also disclosed. Thecomputer-readable medium may comprise, for example, code for monitoring,by the Wi-Fi device, signaling energy on a communication channel in afrequency band associated with the Wi-Fi device, code for comparing themonitored signal energy with a known waveform signature corresponding toLTE operation, and code for identifying a presence of an LTE interfereron the communication channel in the frequency band associated with theWi-Fi device based on the comparison.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are presented to aid in the description ofembodiments of the invention and are provided solely for illustration ofthe embodiments and not limitation thereof.

FIG. 1 illustrates an example wireless communication networkdemonstrating the principles of multiple access communication.

FIG. 2 is a block diagram conceptually illustrating an example framestructure in downlink LTE communications.

FIG. 3 is a block diagram conceptually illustrating an example framestructure in uplink LTE communications.

FIG. 4 illustrates an example mixed LTE communication networkenvironment in which small cell base stations are deployed inconjunction with macro cell eNBs.

FIG. 5 illustrates an example mixed communication network environment inwhich LTE small cells (LTE SCs) are deployed in proximity with Wi-Fiaccess points (Wi-Fi APs).

FIG. 6 is a signaling flow diagram illustrating an example method ofmanaging co-channel LTE interference by a Wi-Fi AP in a wirelesscommunication network.

FIG. 7 illustrates different LTE radio frame UL/DL configurations.

FIG. 8 is a signaling flow diagram illustrating an example of anSTA-assisted method of managing co-channel LTE interference by a Wi-FiAP in a wireless communication network.

FIG. 9 illustrates the configuration of an example Wi-Fi AP for managingco-channel LTE interference in a wireless communication network.

FIG. 10 illustrates the configuration of an example Wi-Fi STA forassisting a Wi-Fi AP in managing co-channel LTE interference in awireless communication network.

FIG. 11 is a flow diagram illustrating an example method forinterference management by a Wi-Fi device.

FIG. 12 illustrates in more detail the principles of wirelesscommunication between a wireless device (e.g., a base station) and awireless device (e.g., a user device) of a sample communication systemthat may be adapted as described herein.

FIG. 13 illustrates an example Wi-Fi apparatus represented as a seriesof interrelated functional modules.

DETAILED DESCRIPTION

In relation to the background above, techniques are described herein toprovide improved interference management for Wi-Fi devices operating inthe unlicensed frequency bands along with other radio accesstechnologies including Long Term Evolution (LTE), without the need foradditional and expensive LTE hardware. As is explained in more detailbelow, using its existing Wi-Fi hardware, such devices may be configuredto identify LTE interferers operating in the unlicensed spectrum,classify the type of interference observed, take appropriate avoidanceor mitigation action to address it, and so on.

Various aspects of the invention are disclosed in the followingdescription and related drawings directed to specific aspects disclosed.Alternate aspects may be devised without departing from the scope of theinvention. Additionally, well-known elements of the invention will notbe described in detail or will be omitted so as not to obscure therelevant details of the invention.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any embodiment described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other embodiments. Likewise, the term “embodiments ofthe invention” does not require that all embodiments of the inventioninclude the discussed feature, advantage or mode of operation. It willtherefore be appreciated that the terminology used herein is for thepurpose of describing particular embodiments only and is not intended tobe limiting of embodiments of the invention. As used herein, thesingular forms “a,” “an,” and “the” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. It willbe further understood that the terms “comprises,” “comprising,”“includes,” and/or “including,” when used herein, specify the presenceof stated features, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, integers, steps, operations, elements, components,and/or groups thereof.

FIG. 1 illustrates an example wireless communication networkdemonstrating the principles of multiple access communication. Theillustrated wireless communication network 100 is configured to supportcommunication between a number of users. As shown, the wirelesscommunication network 100 may be divided into one or more cells 102,such as the illustrated cells 102A-102G. Communication coverage in cells102A-102G may be provided by one or more base stations 104, such as theillustrated base stations 104A-104G. In this way, each base station 104may provide communication coverage to a corresponding cell 102. The basestation 104 may interact with a plurality of user devices 106, such asthe illustrated user devices 106A-106L.

Each user device 106 may communicate with one or more of the basestations 104 on a downlink (DL) and/or an uplink (UL). In general, a DLis a communication link from a base station to a user device, while anUL is a communication link from a user device to a base station. Thebase stations 104 may be interconnected by appropriate wired or wirelessinterfaces allowing them to communicate with each other and/or othernetwork equipment. Accordingly, each user device 106 may alsocommunicate with another user device 106 through one or more of the basestations 104. For example, the user device 106J may communicate with theuser device 106H in the following manner: the user device 106J maycommunicate with the base station 104D, the base station 104D may thencommunicate with the base station 104B, and the base station 104B maythen communicate with the user device 106H, allowing communication to beestablished between the user device 106J and the user device 106H.

The wireless communication network 100 may provide service over a largegeographic region. For example, the cells 102A-102G may cover a fewblocks within a neighborhood or several square miles in a ruralenvironment. In some systems, each cell may be further divided into oneor more sectors (not shown). In addition, the base stations 104 mayprovide the user devices 106 access within their respective coverageareas to other communication networks, such as the Internet or anothercellular network. Each user device 106 may be a wireless communicationdevice (e.g., a mobile phone, router, personal computer, server, etc.)used by a user to send and receive voice or data over a communicationsnetwork, and may be alternatively referred to as an Access Terminal(AT), a Mobile Station (MS), a User Equipment (UE), etc. In the exampleshown in FIG. 1, the user devices 106A, 106H, and 106J comprise routers,while the user devices 106B-106G, 1061, 106K, and 106L comprise mobilephones. Again, however, each of the user devices 106A-106L may compriseany suitable communication device.

For their wireless air interfaces, each base station 104 may operateaccording to one of several Radio Access Technologies (RATs) dependingon the network in which it is deployed, and may be alternativelyreferred to as a NodeB, evolved NodeB (eNB), etc. These networks mayinclude, for example, Code Division Multiple Access (CDMA) networks,Time Division Multiple Access (TDMA) networks, Frequency DivisionMultiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks,Single-Carrier FDMA (SC-FDMA) networks, and so on. The terms “network”and “system” are often used interchangeably. A CDMA network mayimplement a RAT such as Universal Terrestrial Radio Access (UTRA),cdma2000, etc. UTRA includes Wideband-CDMA (W-CDMA) and Low Chip Rate(LCR). cdma2000 covers IS-2000, IS-95 and IS-856 standards. A TDMAnetwork may implement a RAT such as Global System for MobileCommunications (GSM). An OFDMA network may implement a RAT such asEvolved UTRA (E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20,Flash-OFDM®, etc. UTRA, E-UTRA, and GSM are part of Universal MobileTelecommunication System (UMTS). Long Term Evolution (LTE) is a releaseof UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS, and LTE are describedin documents from an organization named “3rd Generation PartnershipProject” (3GPP). cdma2000 is described in documents from an organizationnamed “3rd Generation Partnership Project 2” (3GPP2). These documentsare publicly available.

FIG. 2 is a block diagram conceptually illustrating an example framestructure in downlink LTE communications. In LTE, the base stations 104of FIG. 1 are generally referred to as eNBs and the user devices 106 aregenerally referred to as UEs. The transmission timeline for the downlinkmay be partitioned into units of radio frames. Each radio frame may havea predetermined duration (e.g., 10 milliseconds (ms)) and may bepartitioned into 10 subframes with indices of 0 through 9. Each subframemay include two slots. Each radio frame may thus include 20 slots withindices of 0 through 19. Each slot may include L symbol periods, e.g., 7symbol periods for a normal cyclic prefix (as shown in FIG. 2) or 6symbol periods for an extended cyclic prefix. The 2L symbol periods ineach subframe may be assigned indices of 0 through 2L−1. The availabletime frequency resources may be partitioned into resource blocks. Eachresource block may cover N subcarriers (e.g., 12 subcarriers) in oneslot.

In LTE, an eNB may send a Primary Synchronization Signal (PSS) and aSecondary Synchronization Signal (SSS) for each cell in the eNB. The PSSand SSS may be sent in symbol periods 5 and 6, respectively, in each ofsubframes 0 and 5 of each radio frame with the normal cyclic prefix, asshown in FIG. 2. The synchronization signals may be used by UEs for celldetection and acquisition. The eNB may send a Physical Broadcast Channel(PBCH) in symbol periods 0 to 3 in slot 1 of subframe 0. The PBCH maycarry certain system information.

Reference signals are transmitted during the first and fifth symbolperiods of each slot when the normal cyclic prefix is used and duringthe first and fourth symbol periods when the extended cyclic prefix isused. For example, the eNB may send a Cell-specific Reference Signal(CRS) for each cell in the eNB on all component carriers. The CRS may besent in symbols 0 and 4 of each slot in case of the normal cyclicprefix, and in symbols 0 and 3 of each slot in case of the extendedcyclic prefix. The CRS may be used by UEs for coherent demodulation ofphysical channels, timing and frequency tracking, Radio Link Monitoring(RLM), Reference Signal Received Power (RSRP), and Reference SignalReceived Quality (RSRQ) measurements, etc.

The eNB may send a Physical Control Format Indicator Channel (PCFICH) inthe first symbol period of each subframe, as seen in FIG. 2. The PCFICHmay convey the number of symbol periods (M) used for control channels,where M may be equal to 1, 2, or 3 and may change from subframe tosubframe. M may also be equal to 4 for a small system bandwidth, e.g.,with less than 10 resource blocks. In the example shown in FIG. 2, M=3.The eNB may send a Physical HARQ Indicator Channel (PHICH) and aPhysical Downlink Control Channel (PDCCH) in the first M symbol periodsof each subframe. The PDCCH and PHICH are also included in the firstthree symbol periods in the example shown in FIG. 2. The PHICH may carryinformation to support Hybrid Automatic Repeat Request (HARQ). The PDCCHmay carry information on resource allocation for UEs and controlinformation for downlink channels. The eNB may send a Physical DownlinkShared Channel (PDSCH) in the remaining symbol periods of each subframe.The PDSCH may carry data for UEs scheduled for data transmission on thedownlink. The various signals and channels in LTE are described in 3GPPTS 36.211, entitled “Evolved Universal Terrestrial Radio Access(E-UTRA); Physical Channels and Modulation,” which is publiclyavailable.

The eNB may send the PSS, SSS, and PBCH in the center 1.08 MHz of thesystem bandwidth used by the eNB. The eNB may send the PCFICH and PHICHacross the entire system bandwidth in each symbol period in which thesechannels are sent. The eNB may send the PDCCH to groups of UEs incertain portions of the system bandwidth. The eNB may send the PDSCH tospecific UEs in specific portions of the system bandwidth. The eNB maysend the PSS, SSS, PBCH, PCFICH, and PHICH in a broadcast manner to allUEs, may send the PDCCH in a unicast manner to specific UEs, and mayalso send the PDSCH in a unicast manner to specific UEs.

A number of resource elements may be available in each symbol period.Each resource element may cover one subcarrier in one symbol period andmay be used to send one modulation symbol, which may be a real orcomplex value. Resource elements not used for a reference signal in eachsymbol period may be arranged into Resource Element Groups (REGs). EachREG may include four resource elements in one symbol period. The PCFICHmay occupy four REGs, which may be spaced approximately equally acrossfrequency, in symbol period 0. The PHICH may occupy three REGs, whichmay be spread across frequency, in one or more configurable symbolperiods. For example, the three REGs for the PHICH may all belong insymbol period 0 or may be spread in symbol periods 0, 1, and 2. ThePDCCH may occupy 9, 18, 32, or 64 REGs, which may be selected from theavailable REGs, in the first M symbol periods. Only certain combinationsof REGs may be allowed for the PDCCH.

A UE may know the specific REGs used for the PHICH and the PCFICH. TheUE may search different combinations of REGs for the PDCCH. The numberof combinations to search is typically less than the number of allowedcombinations for the PDCCH. An eNB may send the PDCCH to the UE in anyof the combinations that the UE will search.

FIG. 3 is a block diagram conceptually illustrating an example framestructure in uplink LTE communications. The available resource blocks(which may be referred to as RBs) for the uplink may be partitioned intoa data section and a control section. The control section may be formedat the two edges of the system bandwidth and may have a configurablesize. The resource blocks in the control section may be assigned to UEsfor transmission of control information. The data section may includeall resource blocks not included in the control section. The design inFIG. 3 results in the data section including contiguous subcarriers,which may allow a single UE to be assigned all of the contiguoussubcarriers in the data section.

A UE may be assigned resource blocks in the control section to transmitcontrol information to an eNB. The UE may also be assigned resourceblocks in the data section to transmit data to the eNodeB. The UE maytransmit control information in a Physical Uplink Control Channel(PUCCH) on the assigned resource blocks in the control section. The UEmay transmit only data or both data and control information in aPhysical Uplink Shared Channel (PUSCH) on the assigned resource blocksin the data section. An uplink transmission may span both slots of asubframe and may hop across frequency as shown in FIG. 3.

The PSS, SSS, CRS, PBCH, PUCCH, and PUSCH in LTE on an unlicensed bandare otherwise the same or substantially the same as in LTE as describedin 3GPP TS 36.211, entitled “Evolved Universal Terrestrial Radio Access(E-UTRA); Physical Channels and Modulation,” which is publiclyavailable.

As discussed briefly in the background above, smaller scale coveragebase stations referred to as “small cell” base stations have recentlybegun to be deployed in conjunction with conventional larger scalecoverage base stations such as those illustrated in FIG. 1, which maytherefore be referred to as “macro cell” base stations. As a user devicemoves through mixed communication network environments providing bothmacro cell and small cell coverage, the user device may be served incertain locations by macro cell base stations and at other locations bysmall cell base stations. Small cell base stations may be used toprovide significant capacity growth, in-building coverage, and in somecases different services for a more robust user experience.

FIG. 4 illustrates an example mixed LTE communication networkenvironment in which small cell base stations are deployed inconjunction with macro cell eNBs. As shown, an eNB 405 may providecommunication coverage to one or more UEs, such as the illustrated UEs420, 421, and 422, within a macro cell coverage area 430 (as discussedabove in more detail with reference to FIG. 1), while small cell basestations 410 and 412 may provide their own communication coverage withinrespective small cell coverage areas 415 and 417, with varying degreesof overlap among the different coverage areas. It is noted that certainsmall cells may be restricted in some manner, such as for associationand/or registration, and may therefore be referred to as ClosedSubscriber Group (“CSG”) cells. In this example, at least some UEs, suchas the illustrated UE 422, may be capable of operating both in macroenvironments (e.g., macro areas) and in smaller scale networkenvironments (e.g., residential, femto areas, pico areas, etc.) asshown.

Turning to the illustrated connections in more detail, the UE 420 maygenerate and transmit a message via a wireless link to the eNB 405, themessage including information related to various types of communication(e.g., voice, data, multimedia services, etc.). The UE 422 may similarlycommunicate with the small cell base station 410 via a wireless link,and the UE 421 may similarly communicate with the small cell basestation 412 via a wireless link. The eNB 405 may also communicate with acorresponding wide area or external network 440 (e.g., the Internet),via a wired link or via a wireless link, while the small cell basestations 410 and 412 may also similarly communicate with the network440, via their own wired or wireless links. For example, the small cellbase stations 410 and 412 may communicate with the network 440 by way ofan Internet Protocol (IP) connection, such as via a Digital SubscriberLine (DSL, e.g., including Asymmetric DSL (ADSL), High Data Rate DSL(HDSL), Very High Speed DSL (VDSL), etc.), a TV cable carrying IPtraffic, a Broadband over Power Line (BPL) connection, an Optical Fiber(OF) cable, or some other link.

The network 440 may comprise any type of electronically connected groupof computers and/or devices, including, for example, the followingnetworks: Internet, Intranet, Local Area Networks (LANs), or Wide AreaNetworks (WANs). In addition, the connectivity to the network may be,for example, by remote modem, Ethernet (IEEE 802.3), Token Ring (IEEE802.5), Fiber Distributed Datalink Interface (FDDI) AsynchronousTransfer Mode (ATM), Wireless Ethernet (IEEE 802.11), Bluetooth (IEEE802.15.1), or some other connection. As used herein, the network 440includes network variations such as the public Internet, a privatenetwork within the Internet, a secure network within the Internet, aprivate network, a public network, a value-added network, an intranet,and the like. In certain systems, the network 440 may also comprise aVirtual Private Network (VPN).

Accordingly, it will be appreciated that the eNB 405 and/or either orboth of the small cell base stations 410 and 412 may be connected to thenetwork 440 using any of a multitude of devices or methods. Theseconnections may be referred to as the “backbone” or the “backhaul” ofthe network, and may in some implementations be used to manage andcoordinate communications between the eNB 405, the small cell basestation 410, and the small cell base station 412. In this way, dependingon the current location of the UE 422, for example, the UE 422 mayaccess the communication network 440 by the eNB 405 or by the small cellbase station 410.

In this example, the eNB 405 and the small cell base stations 410 and412 each operate in accordance with an LTE implementation. Typically,such LTE operations are confined to one or more licensed frequency bandsthat have been reserved (e.g., by the Federal Communications Commission(FCC)) for such communications. However, certain communication systems,in particular those employing small cell base stations as in the designof FIG. 4, have extended LTE operations into unlicensed frequency bandssuch as the Unlicensed National Information Infrastructure (UNII) bandused by Wireless Local Area Network (WLAN) technologies. Forconvenience, this type of LTE operation on an unlicensed RF band may bereferred to herein as LTE/LTE Advanced in unlicensed spectrum, or simplyas “LTE” in the surrounding context.

In some systems, LTE operation may be supplemental to licensed bandoperation by employing one or more unlicensed carriers operating in anunlicensed portion of the wireless spectrum in conjunction with ananchor licensed carrier operating in a licensed portion of the wirelessspectrum (e.g., LTE Supplemental DownLink (SDL)), or it may be astandalone configuration operating exclusively in an unlicensed portionof the wireless spectrum without the use of an anchor licensed carrier(e.g., LTE Standalone). SDL in general refers to operation in a carrieraggregation mode where the primary carrier is an FDD paired DL and UL,and an additional DL carrier is used as the SDL. In an LTEimplementation including unlicensed spectrum operation, the SDL carriermay be an unlicensed carrier and the primary FDD UL/DL carrier may be alicensed carrier. When carriers are aggregated, each carrier may bereferred to as a component carrier.

The extension of small cell LTE operation into unlicensed frequencybands such as the UNII band may increase spectral efficiency and hencecapacity of the LTE system. As discussed briefly in the backgroundabove, however, it may also encroach on the operations of other radioaccess technologies that typically utilize the same unlicensed band,most notably IEEE 802.11x WLAN technologies generally referred to as“Wi-Fi.”

FIG. 5 illustrates an example mixed communication network environment inwhich LTE small cells (LTE SCs) are deployed in proximity with Wi-Fiaccess points (Wi-Fi APs). For illustration purposes, an example Wi-FiAP 510 is shown as serving various subscriber stations (STAs) 512 and514, while a loaded LTE SC 520 is shown as serving a UE 522 in proximityto the Wi-Fi AP 510 and an unloaded LTE SC 530 also operates nearby.This communication environment creates several sources of potentialco-channel interference for the Wi-Fi AP 510.

As shown, one source of co-channel interference is DL signaling by theunloaded LTE SC 530. This signaling generally includes broadcastedsynchronization and discovery signaling such as the PSS signals, SSSsignals, and CRS signals described above with reference to FIG. 2. Thisinterference may impact any Wi-Fi device in range, including the Wi-FiAP 510 as well as the STA 514. Another source of co-channel interferenceis DL signaling from the loaded LTE SC 520. This signaling generallyincludes not only the same broadcasted synchronization and discoverysignaling, but also data transmissions to the UE 522. This interferencemay similarly impact any Wi-Fi device in range, including the STA 512.Another source of co-channel interference is UL signaling from the UE522. This signaling generally includes data and control information suchas the PUSCH signals and PUCCH signals described above with reference toFIG. 2. This interference may similarly impact any Wi-Fi device inrange, including the Wi-Fi AP 510 as well as the STA 512.

According to various designs provided herein, the Wi-Fi AP 510 maytherefore be specially programmed or configured to identify the presenceof LTE interference and take appropriate action to address it, withoutthe need for additional and expensive LTE-specific hardware such as adedicated LTE receiver. The Wi-Fi AP 510 may also be speciallyprogrammed or configured to classify the type of LTE interferenceidentified and tailor any interference avoidance or mitigation actionsto better address the type of interference observed.

FIG. 6 is a signaling flow diagram illustrating an example method ofmanaging co-channel LTE interference by a Wi-Fi AP in a wirelesscommunication network. As will be discussed in more detail below, anequivalent method may be performed by any Wi-Fi device including bothWi-Fi APs and STAs, acting alone or in combination (e.g., STA-assisted).For illustration purposes, however, FIG. 6 is shown in the context ofoperations performed by the Wi-Fi AP 510 of FIG. 5.

In this example, the Wi-Fi AP 510 monitors signaling energy (e.g., theFast Fourier Transform (FFT) energy output) on a communication channelin a frequency band associated with its typical operations, such as theUNII band or some other unlicensed frequency band (block 610). Becauseof the proximity of the LTE SC 530 to the Wi-Fi AP 510, as shown in FIG.5, the monitored signal energy includes LTE signaling 602 from the LTESC 530. Although the Wi-Fi AP 510 is not provisioned with a dedicatedLTE receiver, it is able to monitor signaling energy within itsfrequency band of operation using its own WLAN receiver circuitry.

Since the Wi-Fi AP 510 is not synced to the LTE subframe boundary, anappropriate measurement interval may be selected and repeated based onthe LTE frame structure to more accurately capture useful signal energyinformation. For example, the measurement interval may span at least oneLTE slot duration (i.e., 0.5 ms) and at most one LTE subframe duration(i.e., 1 ms). The measurements may then be repeated in accordance withthe LTE subframe periodicity (i.e., 1 ms) for a duration in accordancewith the LTE frame duration (i.e., 10 ms). In some designs, themeasurements may be aggregated over multiple LTE frame duration periods,for example, with random time offsets for more confidence.

Once the measurements are collected, the Wi-Fi AP 510 can compare themonitored signal energy with a known waveform signature (which may alsobe referred to as a fingerprint) corresponding to LTE (block 620) andidentify therefrom the presence of any LTE interferers (block 630). Forexample, the DL PSS signals, SSS signals, and CRS signals describedabove with reference to FIG. 2 are each broadcast with a characteristicperiodicity that can be used to define such a waveform signaturepattern. PSS/SSS signals are sent on the center 62 subcarriers of allcomponent carriers in the last OFDM symbol of the 1st slot and 11th slot(i.e., twice every 10 ms) in every radio frame by the LTE SC 530irrespective of the operating bandwidth. The periodicity of the FFTenergy output in center frequency bins can accordingly be patternmatched to identify the presence of nearby unloaded LTE SCs such as theLTE SC 530 based on a PSS/SSS signature pattern. Similarly, CRS signalsare sent on OFDM symbols 0, 4, 7, and 11 in every DL subframe on allcomponent carriers by the LTE SC 530 and appear wideband to the Wi-Fi AP510 due to the different subcarrier spacing (WLAN subcarrierspacing=312.5 kHz, whereas LTE subcarrier spacing=15 kHz). Theperiodicity of the FFT energy output can be similarly pattern matched toidentify the presence of nearby unloaded LTE SCs such as the LTE SC 530based on a PSS/SSS, CRS signature pattern.

Returning to FIG. 6, as another example, certain LTE UL signals 604transmitted by the UE 522 such as PUCCH signals may also be sent with acharacteristic periodicity that can be used to define a known waveformsignature pattern. Hopping PUCCH transmissions, for example, which areout-of-band for Wi-Fi, may be used to detect the presence of a nearbyLTE UE such as the UE 522. Downlink signaling from the LTE SC 530,however, may be easier to reliably detect compared to uplink signalingby the UE 522 because LTE small cell transmission power is usuallysignificantly higher than UE transmission power, LTE SCs are guaranteedto transmit CRS symbols in every DL subframe on all component carriers,there is generally a DL-UL traffic asymmetry, and so on. Detecting LTESC transmissions may also be more critical compared to detecting UEtransmissions because unloaded cell transmissions are more frequent andhigher power. In most scenarios, the LTE SC transmissions cause moreharm to a Wi-Fi device than do nearby UE transmissions.

In either case, the interference identification may be repeated over aperiod of time as shown in FIG. 6 for accuracy, as bursty data trafficmay temporarily obscure any pattern matching. For example, on thedownlink, PDSCH data transmissions may be present during some subframesand may wash out the periodicity of PSS, SSS, and CRS signal energies inthose subframes. Similarly, on the uplink, PUSCH data transmissions maybe present during some subframes and may wash out the periodicity ofPUCCH signal energies in those subframes. Nevertheless, datatransmissions are generally intermittent whereas control signaling andin particular pilot/discovery signaling are fairly constant.Accordingly, measurements repeated over a sufficient number ofiterations will tend to produce reliable pattern matching results.

In some designs, once an LTE interferer has been identified, the Wi-FiAP 510 may perform further match processing on the resulting signalenergy pattern to classify the type of interference being observed intoone of several possible LTE configurations (block 640). The differentLTE configurations correspond to different UL/DL sharing patterns of thedifferent subframes making up each radio frame. As discussed in moredetail below, each different LTE configuration presents a differentinterference pattern that may be managed differently by the Wi-Fi AP 510once identified.

FIG. 7 illustrates different LTE radio frame UL/DL configurations andtheir corresponding interference patterns. Here, ‘D’ indicates a DLsubframe designated for DL transmissions (i.e., eNB to UEcommunications), ‘U’ indicates an UL subframe for UL transmissions(i.e., UE to eNB communications), and ‘S’ indicates a special subframe.A special subframe may include DL OFDM symbols, a guard period, and ULOFDM symbols.

As discussed in more detail above, when the LTE SC 530 operates in SDLmode, the unlicensed spectrum may be utilized only for DL transmissions.Accordingly, each of the subframes 0-9 of a given radio frame in an SDLconfiguration is designated ‘D’ for DL transmission. By contrast, whenthe LTE SC 530 operates in Standalone mode, the unlicensed spectrum maybe utilized for both DL and UL transmissions, according to one of theillustrated Time Division Duplexing (TDD) UL/DL configurations. Thereare seven total such configurations defined for LTE-TDD spectrumsharing, indexed as UL/DL configurations 0-6. As shown, UL/DLconfigurations 0-2 and 6 repeat their characteristic pattern twicewithin a given subframe, and therefore have effective periodicities of 5ms. Meanwhile, UL/DL configurations 3-5 have respective characteristicpatterns that span an entire subframe, and therefore have effectiveperiodicities of 10 ms.

Returning to FIG. 6, the Wi-Fi AP 510 may classify the type ofinterference being observed (block 640) by comparing the monitoredsignal energy pattern to the different UL/DL configurations in FIG. 7.In contrast to the initial interference identification which may operateat a granularity commensurate with the periodicity of the LTE signalsthemselves (i.e., on the order of individual subframes), theinterference classification may operate at a larger granularitycommensurate with the periodicity of the different UL/DL configurations(i.e., on the order of whole frames). By determining the durationsbetween time periods identified as matching DL subframe interferencepatterns, for example, the Wi-Fi AP 510 may distinguish DL subframes(where such interference is expected) and UL subframes (where suchinterference is not expected), and correlate the observed UL/DL patternto one of the different UL/DL configurations in FIG. 7. Conversely, bydetermining the durations between time periods identified as matching ULsubframe interference patterns, the Wi-Fi AP 510 may also distinguish ULsubframes (where such interference is expected) and DL subframes (wheresuch interference is not expected), and correlate the observed UL/DLpattern to one of the different UL/DL configurations in FIG. 7.

Based on the identification and, in some cases, classification of an LTEinterferer, the Wi-Fi AP 510 may perform interference avoidance and/ormitigation as appropriate (block 650). For example, in order to avoidLTE interference identified on a communication channel, the Wi-Fi AP 510may perform smart channel selection and switch operating channels in thepresence of such interference. The switching may be based on a switchingthreshold (e.g., an interference power threshold, a PER threshold, etc.)associated with the presence of the LTE interferer. The Wi-Fi AP 510 mayalso block or prevent transmission to or from its associated STAs 512,514 during high interference periods. This may be achieved, for example,by sending a Clear-To-Send-to-Self (CTS2S) message to reserve thecommunication medium and prevent traffic in the Wi-Fi network duringsuch time periods.

The Wi-Fi AP 510 may also perform other more advanced interferencemitigation techniques based on the classification of the LTEinterference and knowledge of the UL/DL configuration being employed.For example, the Wi-Fi AP 510 may perform dual-rate control based on theUL/DL configuration, whereby separate power tracking loops aremaintained for (1) packet transmissions during LTE DL subframes and (2)packet transmissions during LTE UL subframes. As discussed above, theobserved interference will generally be different between DL subframesin which the LTE SCs themselves transmit and UL subframes in which UEsmay or may not transmit. Separate power tracking loops enables moreindividualized tracking for these different time periods, rather thanrequiring them to be indiscriminately averaged together.

As another example, the Wi-Fi AP 510 may schedule the different STAs512, 514 at different times depending on the interference pattern. Forinstance, if the STA 514 suffers from larger DL interference than theSTA 512, it can be scheduled during known UL periods of the determinedUL/DL configuration while the STA 512 with less interference may be moreflexible and scheduled anytime. The Wi-Fi AP 510 may also alignimportant transmissions such as beacons with UL timing to reduce theimpact from DL interference (e.g., if STA feedback identifies moreinterference on the DL).

As another example, the Wi-Fi AP 510 may perform smart TransmissionOpportunity (TXOP) scheduling to align (and/or shorten) itscommunications with the known or at least approximately known UL/DLsubframe boundaries of an identified UL/DL configuration. This helps toavoid or at least reduce TXOP leakage across UL/DL subframe boundariesand again provides a more consistent interference level acrosstransmissions, which can be addressed via conventional techniques suchas lowering the data rate for increased integrity, etc.

As another example, if the Wi-Fi AP 510 is equipped with multipleantennas, it may perform interference nulling (e.g., using directionaltransmission/reception). In this way, it may estimate the direction of astrong LTE SC and null it out. Given the relative stationarity of bothLTE SCs and Wi-Fi APs, nulling may provide a fairly consistent reductionin interference. The estimation may be performed based CRStransmissions, for example, where CRS is repeated and the receivedsignals can be canceled.

As discussed above, it will be appreciated that the techniques hereinallow the Wi-Fi device to identify an LTE interferer by monitoring andprocessing (either directly or assisted) signaling energy, without theneed for additional and expensive LTE-specific hardware such as adedicated LTE receiver. This is in contrast to conventional techniquesfor Wi-Fi APs that have access to LTE receiver circuitry, such as thosethat are physically or logically “co-located” with an LTE SC, where,instead of monitoring and processing signaling energy, the Wi-Fi AP maysimply use the LTE SC circuitry to identify LTE transmissions on itsoperating channel (e.g., using a Network Listen Module (NLM) of the LTESC or one of its associated UEs) and query the LTE SC for its UL/DLconfiguration.

FIG. 8 is a signaling flow diagram illustrating an example of anSTA-assisted method of managing co-channel LTE interference by a Wi-FiAP in a wireless communication network. This example is similar to thatdescribed above with reference to FIG. 6 except that the Wi-Fi AP 510 isassisted by the STA 512, which may perform some of the operations. Inthis example, it is the STA 512 that monitors signaling energy on acommunication channel in the unlicensed frequency band (block 810).Because of the proximity of the LTE SC 520 to the STA 512, as shown inFIG. 5, the monitored signal energy includes LTE signaling 802 from theLTE SC 520. Again, the STA 512 need not be provisioned with a dedicatedLTE receiver, as it is able to nevertheless monitor signaling energywithin its frequency band of operation using its own WLAN receivercircuitry.

Based on the monitored signal energy, the STA 512 may generate aninterference report 804 and send it to the Wi-Fi AP 510 for furtherprocessing. The interference report 804 may take the form of rawmeasurement data simply collected and forwarded on by the STA 512, ormay be further processed as desired. For example, the interferencereport 804 may include a noise histogram over successive (e.g., 10 ms)time periods with randomized measurement start times that enable theWi-Fi AP 510 to determine if the histogram has a periodic pattern, orthe interference report 804 may be a Radio Resource Measurement (RRM)report as defined in IEEE 802.11k.

The Wi-Fi AP 510 may then perform further processing including comparingthe monitored signal energy from the interference report with a knownwaveform signature pattern corresponding to LTE (block 820), identifyingtherefrom the presence of any LTE interferers (block 830), classifyingthe type of interference being observed (block 840), and performinginterference avoidance and/or mitigation as appropriate (block 850).Alternatively, some or all of these processing operations may beperformed by the STA 512 itself (blocks 860-890), upon which a final (orother intermediate) interference report 806 may be generated and sent tothe Wi-Fi AP 510 as shown.

FIG. 9 illustrates the configuration of an example Wi-Fi AP for managingco-channel LTE interference in a wireless communication network. In thisexample, a Wi-Fi AP 910 is deployed in the vicinity of an LTE SC 930 andan LTE UE 940. The Wi-Fi AP 910 may serve one or more STAs 950, shown inthe singular for illustration purposes.

In general, the Wi-Fi AP 910 includes various components for providingand processing services related to over-the-air and backhaulconnectivity. For example, the Wi-Fi AP 910 may include a transceiver912 for over-the-air WLAN communication with the STAs 950 and a backhaulcontroller 914 for backhaul communications with other network devices.These components may operate under the direction of a processor 916 inconjunction with memory 918, for example, all of which may beinterconnected via a bus 920 or the like.

In addition and in accordance with the discussion above, the Wi-Fi AP910 may also further include a signal energy monitor 922 for monitoringsignaling energy on a communication channel in the unlicensed frequencyband, a waveform comparator 924 for comparing the monitored signalenergy with a known waveform signature corresponding to LTE (e.g., froman LTE waveform signatures database 919 stored in the memory 918), andan interference identifier 926 for identifying therefrom the presence ofany LTE interferers. The Wi-Fi AP 910 may also include an interferenceclassifier 928 for classifying the type of interference being observedand an interference moderator 929 for performing interference avoidanceand/or mitigation as appropriate. It will be appreciated that in somedesigns one or more or all of these operations may be performed by or inconjunction with the processor 916 and memory 918.

FIG. 10 illustrates the configuration of an example Wi-Fi STA forassisting a Wi-Fi AP in managing co-channel LTE interference in awireless communication network. In this example, an STA 1050 assisting aWi-Fi AP 1010 is deployed in the vicinity of an LTE SC 1030 and an LTEUE 1040, which may or may not be directly visible to the Wi-Fi AP 1010.The Wi-Fi AP 1010 may serve the STA 1050 along with one or more otherSTAs (not shown).

In general, the STA 1050 includes various components for providing andprocessing services related to over-the-air connectivity. For example,the STA 1050 may include a transceiver 1012 for over-the-air WLANcommunication with the Wi-Fi AP 1010, which may operate under thedirection of a processor 1016 in conjunction with memory 1018, forexample, all of which may be interconnected via a bus 1020 or the like.

In addition and in accordance with the discussion above, the STA 1050may also further include a signal energy monitor 1022 for monitoringsignaling energy on a communication channel in the unlicensed frequencyband and an interference reporter 1014 for reporting signal energymeasurements or other information (e.g., 802.11k RRM reports) to theWi-Fi AP 1010. Depending on the amount of processing performed directly,the STA 1050 may also include a waveform comparator 1024 for comparingthe monitored signal energy with a known waveform signaturecorresponding to LTE (e.g., from an LTE waveform signatures database1019 stored in the memory 1018), an interference identifier 1026 foridentifying therefrom the presence of any LTE interferers, aninterference classifier 1028 for classifying the type of interferencebeing observed, and an interference moderator 1029 for performinginterference avoidance and/or mitigation as appropriate. It will beappreciated that in some designs one or more or all of these operationsmay be performed by or in conjunction with the processor 1016 and memory1018.

FIG. 11 is a flow diagram illustrating an example method forinterference management by a Wi-Fi device. As shown, the method mayinclude monitoring, by a Wi-Fi device, signaling energy on acommunication channel in a frequency band associated with the Wi-Fidevice (block 1110), comparing the monitored signal energy with a knownwaveform signature corresponding to LTE operation (block 1120), andidentifying a presence of an LTE interferer on the communication channelin the frequency band associated with the Wi-Fi device based on thecomparison (block 1130). The method may also include classifying the LTEinterferer as operating in accordance with one of the UL/DLconfigurations (block 1140) and performing interference avoidance ormitigation in response to identifying the presence of the LTE interferer(block 1150). The classification process may be based on a correlationof a periodicity of the monitored signaling energy with a plurality ofpredefined patterns associated with LTE UL/DL configurations, asdiscussed above with reference to FIG. 7.

As discussed in more detail above, the interference avoidance mayinclude, for example, (a) switching operating channels (e.g., based on aswitching threshold associated with the presence of the LTE interferer)and/or (b) interference-aware, multi-user scheduling of Wi-Fi STAs basedon the UL/DL configuration. The interference mitigation may include, forexample, (a) dual-rate control based on the UL/DL configuration, (b)TXOP scheduling to align with UL/DL subframe boundaries, (c) preventionof transmission during high interference periods (e.g., CTS2S), and/or(d) interference nulling using multiple antennas at the Wi-Fi device.

The methodology of FIG. 11 may be performed by any Wi-Fi deviceincluding both Wi-Fi APs and STAs, acting alone or in combination (e.g.,STA-assisted). For example, the monitoring may be performed by a Wi-FiSTA and the comparing and identifying may be performed by a Wi-Fi AP. Inthis example, the Wi-Fi STA may report to the Wi-Fi AP the monitoredsignal energy (e.g., using the IEEE 802.11k framework). Alternatively,the monitoring may be performed by the Wi-Fi AP directly, using itsWi-Fi receiver circuitry.

FIG. 12 illustrates in more detail the principles of wirelesscommunication between a wireless device 1210 (e.g., a base station) anda wireless device 1250 (e.g., a user device) of a sample communicationsystem 1200 that may be adapted as described herein. At the device 1210,traffic data for a number of data streams is provided from a data source1212 to a transmit (TX) data processor 1214. Each data stream may thenbe transmitted over a respective transmit antenna.

The TX data processor 1214 formats, codes, and interleaves the trafficdata for each data stream based on a particular coding scheme selectedfor that data stream to provide coded data. The coded data for each datastream may be multiplexed with pilot data using OFDM techniques. Thepilot data is typically a known data pattern that is processed in aknown manner and may be used at the receiver system to estimate thechannel response. The multiplexed pilot and coded data for each datastream is then modulated (i.e., symbol mapped) based on a particularmodulation scheme (e.g., BPSK, QSPK, M-PSK, or M-QAM) selected for thatdata stream to provide modulation symbols. The data rate, coding, andmodulation for each data stream may be determined by instructionsperformed by a processor 1230. A data memory 1232 may store programcode, data, and other information used by the processor 1230 or othercomponents of the device 1210.

The modulation symbols for all data streams are then provided to a TXMIMO processor 1220, which may further process the modulation symbols(e.g., for OFDM). The TX MIMO processor 1220 then provides NT modulationsymbol streams to NT transceivers (XCVR) 1222A through 1222T. In someaspects, the TX MIMO processor 1220 applies beam-forming weights to thesymbols of the data streams and to the antenna from which the symbol isbeing transmitted.

Each transceiver 1222 receives and processes a respective symbol streamto provide one or more analog signals, and further conditions (e.g.,amplifies, filters, and upconverts) the analog signals to provide amodulated signal suitable for transmission over the MIMO channel. NTmodulated signals from transceivers 1222A through 1222T are thentransmitted from NT antennas 1224A through 1224T, respectively.

At the device 1250, the transmitted modulated signals are received by NRantennas 1252A through 1252R and the received signal from each antenna1252 is provided to a respective transceiver (XCVR) 1254A through 1254R.Each transceiver 1254 conditions (e.g., filters, amplifies, anddownconverts) a respective received signal, digitizes the conditionedsignal to provide samples, and further processes the samples to providea corresponding “received” symbol stream.

A receive (RX) data processor 1260 then receives and processes the NRreceived symbol streams from NR transceivers 1254 based on a particularreceiver processing technique to provide NT “detected” symbol streams.The RX data processor 1260 then demodulates, deinterleaves, and decodeseach detected symbol stream to recover the traffic data for the datastream. The processing by the RX data processor 1260 is complementary tothat performed by the TX MIMO processor 1220 and the TX data processor1214 at the device 1210.

A processor 1270 periodically determines which pre-coding matrix to use(discussed below). The processor 1270 formulates a reverse link messagecomprising a matrix index portion and a rank value portion. A datamemory 1272 may store program code, data, and other information used bythe processor 1270 or other components of the device 1250.

The reverse link message may comprise various types of informationregarding the communication link and/or the received data stream. Thereverse link message is then processed by a TX data processor 1238,which also receives traffic data for a number of data streams from adata source 1236, modulated by a modulator 1280, conditioned by thetransceivers 1254A through 1254R, and transmitted back to the device1210.

At the device 1210, the modulated signals from the device 1250 arereceived by the antennas 1224, conditioned by the transceivers 1222,demodulated by a demodulator (DEMOD) 1240, and processed by a RX dataprocessor 1242 to extract the reverse link message transmitted by thedevice 1250. The processor 1230 then determines which pre-coding matrixto use for determining the beam-forming weights then processes theextracted message.

FIG. 12 also illustrates that the communication components may includeone or more components that perform LTE interference managementoperations for a Wi-Fi device as taught herein. For example, acommunication (COMM.) component 1290 may cooperate with the processor1230 and/or other components of the device 1210 to perform LTEinterference management for Wi-Fi as taught herein. Similarly, acommunication control component 1292 may cooperate with the processor1270 and/or other components of the device 1250 to support LTEinterference management for Wi-Fi as taught herein. It should beappreciated that for each device 1210 and 1250 the functionality of twoor more of the described components may be provided by a singlecomponent. For example, a single processing component may provide thefunctionality of the communication control component 1290 and theprocessor 1230 and a single processing component may provide thefunctionality of the communication control component 1292 and theprocessor 1270.

FIG. 13 illustrates an example Wi-Fi apparatus 1300 represented as aseries of interrelated functional modules. A module for monitoring 1302may correspond at least in some aspects to, for example, a communicationdevice (e.g., a receiver) as discussed herein. A module for comparing1304 may correspond at least in some aspects to, for example, aprocessing system as discussed herein. A module for identifying 1306 maycorrespond at least in some aspects to, for example, a processing systemas discussed herein. An optional module for classifying 1308 maycorrespond at least in some aspects to, for example, a processing systemas discussed herein. An optional module for performing 1304 maycorrespond at least in some aspects to, for example, a communicationdevice (e.g., a transceiver) in conjunction with a processing system asdiscussed herein.

The functionality of the modules of FIG. 10 may be implemented invarious ways consistent with the teachings herein. In some aspects, thefunctionality of these modules may be implemented as one or moreelectrical components. In some aspects, the functionality of theseblocks may be implemented as a processing system including one or moreprocessor components. In some aspects, the functionality of thesemodules may be implemented using, for example, at least a portion of oneor more integrated circuits (e.g., an ASIC). As discussed herein, anintegrated circuit may include a processor, software, other relatedcomponents, or some combination thereof. Thus, the functionality ofdifferent modules may be implemented, for example, as different subsetsof an integrated circuit, as different subsets of a set of softwaremodules, or a combination thereof. Also, it should be appreciated that agiven subset (e.g., of an integrated circuit and/or of a set of softwaremodules) may provide at least a portion of the functionality for morethan one module.

In addition, the components and functions represented by FIG. 10 as wellas other components and functions described herein, may be implementedusing any suitable means. Such means also may be implemented, at leastin part, using corresponding structure as taught herein. For example,the components described above in conjunction with the “module for”components of FIG. 10 also may correspond to similarly designated “meansfor” functionality. Thus, in some aspects one or more of such means maybe implemented using one or more of processor components, integratedcircuits, or other suitable structure as taught herein.

In some aspects, an apparatus or any component of an apparatus may beconfigured to (or operable to or adapted to) provide functionality astaught herein. This may be achieved, for example: by manufacturing(e.g., fabricating) the apparatus or component so that it will providethe functionality; by programming the apparatus or component so that itwill provide the functionality; or through the use of some othersuitable implementation technique. As one example, an integrated circuitmay be fabricated to provide the requisite functionality. As anotherexample, an integrated circuit may be fabricated to support therequisite functionality and then configured (e.g., via programming) toprovide the requisite functionality. As yet another example, a processorcircuit may execute code to provide the requisite functionality.

It should be understood that any reference to an element herein using adesignation such as “first,” “second,” and so forth does not generallylimit the quantity or order of those elements. Rather, thesedesignations may be used herein as a convenient method of distinguishingbetween two or more elements or instances of an element. Thus, areference to first and second elements does not mean that only twoelements may be employed there or that the first element must precedethe second element in some manner. Also, unless stated otherwise a setof elements may comprise one or more elements. In addition, terminologyof the form “at least one of A, B, or C” or “one or more of A, B, or C”or “at least one of the group consisting of A, B, and C” used in thedescription or the claims means “A or B or C or any combination of theseelements.” For example, this terminology may include A, or B, or C, or Aand B, or A and C, or A and B and C, or 2A, or 2B, or 2C, and so on.

Those of skill in the art will appreciate that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Further, those of skill in the art will appreciate that the variousillustrative logical blocks, modules, circuits, and algorithm stepsdescribed in connection with the embodiments disclosed herein may beimplemented as electronic hardware, computer software, or combinationsof both. To clearly illustrate this interchangeability of hardware andsoftware, various illustrative components, blocks, modules, circuits,and steps have been described above generally in terms of theirfunctionality. Whether such functionality is implemented as hardware orsoftware depends upon the particular application and design constraintsimposed on the overall system. Skilled artisans may implement thedescribed functionality in varying ways for each particular application,but such implementation decisions should not be interpreted as causing adeparture from the scope of the present invention.

The methods, sequences and/or algorithms described in connection withthe embodiments disclosed herein may be embodied directly in hardware,in a software module executed by a processor, or in a combination of thetwo. A software module may reside in RAM memory, flash memory, ROMmemory, EPROM memory, EEPROM memory, registers, hard disk, a removabledisk, a CD-ROM, or any other form of storage medium known in the art. Anexemplary storage medium is coupled to the processor such that theprocessor can read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor.

Accordingly, an embodiment of the invention can include a computerreadable media embodying a method for interference management by a Wi-Fidevice. Accordingly, the invention is not limited to illustratedexamples and any means for performing the functionality described hereinare included in embodiments of the invention.

While the foregoing disclosure shows illustrative embodiments of theinvention, it should be noted that various changes and modificationscould be made herein without departing from the scope of the inventionas defined by the appended claims. The functions, steps and/or actionsof the method claims in accordance with the embodiments of the inventiondescribed herein need not be performed in any particular order.Furthermore, although elements of the invention may be described orclaimed in the singular, the plural is contemplated unless limitation tothe singular is explicitly stated.

What is claimed is:
 1. A method for interference management by a Wi-Fidevice, the method comprising: monitoring, by the Wi-Fi device,signaling energy on a communication channel in a frequency bandassociated with the Wi-Fi device; comparing the monitored signalingenergy with a known waveform signature corresponding to a periodicsignaling energy pattern with a predefined transmission interval that ischaracteristic of a Long Term Evolution (LTE) synchronization ortraining signal; and identifying a presence of an LTE interferer on thecommunication channel in the frequency band associated with the Wi-Fidevice based on the comparison.
 2. The method of claim 1, wherein thesynchronization or training signal comprises a Primary SynchronizationSignal (PSS), a Secondary Synchronization Signal (SSS), a Cell-specificReference Signal (CRS), or a combination thereof.
 3. The method of claim2, wherein the predefined transmission interval defines two instances ofthe monitored signaling energy in a 10 ms period and corresponds to aspacing of the PSS in the first and eleventh slots of an LTE radioframe.
 4. The method of claim 2, wherein the predefined transmissioninterval defines two instances of the monitored signaling energy in a 10ms period and corresponds to a spacing of the SSS in the first andeleventh slots of an LTE radio frame.
 5. The method of claim 2, whereinthe predefined transmission interval defines four instances of themonitored signaling energy in a 1 ms period and corresponds to a spacingof the CRS in the first, fifth, eighth, and twelfth symbols of an LTEsubframe.
 6. The method of claim 1, further comprising performinginterference avoidance or mitigation in response to identifying thepresence of the LTE interferer.
 7. The method of claim 1, wherein themonitoring is performed by a Wi-Fi receiver of the Wi-Fi device.
 8. Themethod of claim 1, wherein the monitoring comprises receiving a reportfrom another Wi-Fi device relating to the monitored signaling energy. 9.An apparatus for interference management by a Wi-Fi device, theapparatus comprising: a receiver configured to monitor, by the Wi-Fidevice, signaling energy on a communication channel in a frequency bandassociated with the Wi-Fi device, a processor; and memory coupled to theprocessor, the processor and the memory being configured to: compare themonitored signaling energy with a known waveform signature correspondingto a periodic signaling energy pattern with a predefined transmissioninterval that is characteristic of a Long Term Evolution (LTE)synchronization or training signal, and identify a presence of an LTEinterferer on the communication channel in the frequency band associatedwith the Wi-Fi device based on the comparison.
 10. The apparatus ofclaim 9, wherein the synchronization or training signal comprises aPrimary Synchronization Signal (PSS), a Secondary Synchronization Signal(SSS), a Cell-specific Reference Signal (CRS), or a combination thereof.11. The apparatus of claim 10, wherein the predefined transmissioninterval defines two instances of the monitored signaling energy in a 10ms period and corresponds to a spacing of the PSS in the first andeleventh slots of an LTE radio frame.
 12. The apparatus of claim 10,wherein the predefined transmission interval defines two instances ofthe monitored signaling energy in a 10 ms period and corresponds to aspacing of the SSS in the first and eleventh slots of an LTE radioframe.
 13. The apparatus of claim 10, wherein the predefinedtransmission interval defines four instances of the monitored signalingenergy in a 1 ms period and corresponds to a spacing of the CRS in thefirst, fifth, eighth, and twelfth symbols of an LTE subframe.
 14. Theapparatus of claim 9, wherein the processor and the memory are furtherconfigured to perform interference avoidance or mitigation in responseto identifying the presence of the LTE interferer.
 15. The apparatus ofclaim 9, wherein the receiver corresponds to a Wi-Fi receiver of theWi-Fi device.
 16. The apparatus of claim 9, wherein the receiver isfurther configured to receive a report from another Wi-Fi devicerelating to the monitored signaling energy.
 17. An apparatus forinterference management by a Wi-Fi device, the apparatus comprising:means for monitoring, by the Wi-Fi device, signaling energy on acommunication channel in a frequency band associated with the Wi-Fidevice; means for comparing the monitored signaling energy with a knownwaveform signature corresponding to a periodic signaling energy patternwith a predefined transmission interval that is characteristic of a LongTerm Evolution (LTE) synchronization or training signal; and means foridentifying a presence of an LTE interferer on the communication channelin the frequency band associated with the Wi-Fi device based on thecomparison.
 18. The apparatus of claim 17, wherein the synchronizationor training signal comprises a Primary Synchronization Signal (PSS), aSecondary Synchronization Signal (SSS), a Cell-specific Reference Signal(CRS), or a combination thereof.
 19. The apparatus of claim 18, whereinthe predefined transmission interval defines two instances of themonitored signaling energy in a 10 ms period and corresponds to aspacing of the PSS in the first and eleventh slots of an LTE radioframe.
 20. The apparatus of claim 18, wherein the predefinedtransmission interval defines two instances of the monitored signalingenergy in a 10 ms period and corresponds to a spacing of the SSS in thefirst and eleventh slots of an LTE radio frame.
 21. The apparatus ofclaim 18, wherein the predefined transmission interval defines fourinstances of the monitored signaling energy in a 1 ms period andcorresponds to a spacing of the CRS in the first, fifth, eighth, andtwelfth symbols of an LTE subframe.
 22. The apparatus of claim 17,further comprising means for performing interference avoidance ormitigation in response to identifying the presence of the LTEinterferer.
 23. The apparatus of claim 17, wherein the means formonitoring comprises means for receiving a report from another Wi-Fidevice relating to the monitored signaling energy.
 24. A non-transitorycomputer-readable medium comprising code, which, when executed by aprocessor, cause the processor to perform operations for interferencemanagement by a Wi-Fi device, the non-transitory computer-readablemedium comprising: code for monitoring, by the Wi-Fi device, signalingenergy on a communication channel in a frequency band associated withthe Wi-Fi device; code for comparing the monitored signaling energy witha known waveform signature corresponding to a periodic signaling energypattern with a predefined transmission interval that is characteristicof a Long Term Evolution (LTE) synchronization or training signal; andcode for identifying a presence of an LTE interferer on thecommunication channel in the frequency band associated with the Wi-Fidevice based on the comparison.
 25. The non-transitory computer-readablemedium of claim 24, wherein the synchronization or training signalcomprises a Primary Synchronization Signal (PSS), a SecondarySynchronization Signal (SSS), a Cell-specific Reference Signal (CRS), ora combination thereof.
 26. The non-transitory computer-readable mediumof claim 25, wherein the predefined transmission interval defines twoinstances of the monitored signaling energy in a 10 ms period andcorresponds to a spacing of the PSS in the first and eleventh slots ofan LTE radio frame.
 27. The non-transitory computer-readable medium ofclaim 25, wherein the predefined transmission interval defines twoinstances of the monitored signaling energy in a 10 ms period andcorresponds to a spacing of the SSS in the first and eleventh slots ofan LTE radio frame.
 28. The non-transitory computer-readable medium ofclaim 25, wherein the predefined transmission interval defines fourinstances of the monitored signaling energy in a 1 ms period andcorresponds to a spacing of the CRS in the first, fifth, eighth, andtwelfth symbols of an LTE subframe.
 29. The non-transitorycomputer-readable medium of claim 24, further comprising code forperforming interference avoidance or mitigation in response toidentifying the presence of the LTE interferer.
 30. The non-transitorycomputer-readable medium of claim 24, wherein the code for monitoringcomprises code for receiving a report from another Wi-Fi device relatingto the monitored signaling energy.